One of the things that I currently find very concerning about object variants
is how they can introduce runtime errors when the discriminator is assigned to
in an incorrect manner. As it turns out, there [seems to be a compiler
bug](https://github.com/nim-lang/Nim/issues/6918) that causes not only
exceptions, but undefined behavior when the discriminator is changed. Also see
[this RFC](https://github.com/nim-lang/Nim/issues/6921).
I always prefer catching these sorts of problems at compile time, and it
occurred to me that making the discriminator private could offer a solution in
some cases.
type
Variants* = enum
vaCow, vaPig, vaHorse
MyObj = object
case kind: Variants
of vaCow:
age*: float
of vaPig:
hunger*: Natural
of vaHorse:
name*: string
proc newMyObj*(age: float): MyObj =
MyObj(kind: vaCow, age: age)
proc kind*(o: MyObj): Variants =
o.kind
So, do you think that this is an idomatic/Nim-esque solution? I feel that it
solves the problem of safety when the "kind" will be determined by a
constructor proc and remain constant, as in the example.
I am tempted to use this pattern often, as I highly value memory safety. Will I
encounter pitfalls/confusion with this, or is it an acceptable workaround?
